A major program of the National Institute on Drug Abuse (NIDA) is to develop new pharmacotherapeutics for the treatment of drug addiction. Controlled-release preparations which maintain an effective drug concentration for a long period of time and therefore alleviate the need for frequent drug administration offer advantages over conventional dosage forms. Such preparations are particularly useful in the treatment of drug addiction, because long-term treatment is usually required and patient compliance can be a problem. In addition, sustained-release preparations for the treatment of narcotic addiction could help maximize the existing treatment resources, an issue of increasing importance in view of the concern over the role of intravenous drug abusers in the AIDS epidemic. The purpose of this contract is to develop a clinically useful controlled- release preparation to provide buprenorphine effects for an extended period of time. Buprenorphine is a partial opioid agonist and has been shown to be effective for the treatment of opioid dependence. During the phase I period of the contract, several different microsphere formulations of buprenorphine have been prepared and characterized. The feasibility of developing a controlled-release buprenorphine delivery system has been demonstrated. During the phase II period, the contractor will continue to develop a parental delivery system of buprenorphine suitable for clinical use.